Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is known. The description adds genuine context beyond that: it performs local validation at no cost before sending, requires the sync-schema permission, costs 1 request, and produces warnings/errors and blockedBy on refusal. That is the kind of behavioral detail an agent cannot get from annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose and safety ('without changing anything') are front-loaded, followed by the result shape, the required ordering, and the operational facts. Dense but every clause earns its place; the long first sentence is the only mild strain.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only preview tool with annotations covering safety and an output schema covering return structure, this is complete: it specifies ordering (before apply_schema_sync), permission requirement, cost, and the refusal signal (blockedBy). Nothing an agent needs to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the schema itself documents prune, document, allowRebuild and allowDestructive with defaults and consequences. The description mentions that the document is validated against the sync document schema locally, but adds no syntax or format meaning beyond what the schema already provides, so baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a precise verb+resource ('plan a schema sync', 'what applying a schema sync document would do, without changing anything') and enumerates the exact output surface (lists, indexes, flows, per-field create/update/adopt/delete/no-op). This is unmistakably distinct from the sibling apply_schema_sync, which the description names.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly states when to use it ('Always call this before apply_schema_sync') and what to do with the result ('show the user the plan'), naming the alternative tool. The when-not is implied by the contrast with apply_schema_sync.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.